The ivention relates to a method for recording and/or reproducing digitally coded signals, in particular digital video signals on any recording media, having a throughput reduced to the throughout actually required for the reproduction of a picture and achieved, among other things, by means of interframe and intraframe coding.
To record digital colour pictures containing approximately 216 Mbit/s or raw data, it is necessary to reduce the data to be recorded for a narrow-band channel as represented, for example, by a video recorder. Among others, the following methods for data reduction are known.
1. Intraframe coded pictures. Interframe coding is a known process in which pixels of successive images of the same coordinate position are compared with one another and only the deviation is coded and recorded as information content. If the comparison indicates that no deviations exist, the values are not recorded but are instead regenerated during playback by repeating the pixels of the preceding. In this case the content of a picture is reduced in such a way that the information to be transmitted is reduced by the redundant and/or irrelevant portions.
2. Interframe coded pictures. Interframe coding is a known process in which the pixels of an image, whose mutual positions respective to columns and rows are arranged, for example, in the form of the "5" on a die, are compared and are reduced in their redundant and/or irrelevant components. During this coding only the differences in consecutive frames are recorded.
The disadvantage of the intraframe coded recording lies in the fact that with a throughput required for recording of 10-15 Mbit/s the picture quality is very poor. Less than 10% of the information is recorded.
The disadvantage of the interframe coded recording lies in the fact that it is not possible to start the reproduction at any point of the recording since the information is only relative. The starting frame is missing.